Tailpulses are fast-rising pulse voltages produced by Germanium or scintillator type radiation detector systems when irradiated with gamma photons from radioactive sources, with characteristic rise times of approximately 100 nanoseconds and slow fall times of approximately 100 microseconds, as shown in FIG. 1. For purposes of testing, calibrating, and validating multi-channel analyzers (MCA) used in radiation detection systems, there is a need to artificially generate electronic pulses which mimic or otherwise simulate such tailpulses, since radioactive sources are often not readily available to use for on-location testing of radiation detection equipment, such as for example at ports of entry. Additionally, in order to realistically mimic the tailpulse generation by Germanium and scintillator detectors, pulse amplitudes must vary in a near random pattern and the process of pulse generation must take into account pulse pileup, i.e. the addition or accumulation of tailpulses which takes place when one or more additional tailpulses occur before the previous pulse has decayed, as illustrated in FIG. 2, which is a consequence of random tailpulse timing.
Analog circuits have been used to produce fixed amplitude tailpulses. And commercially available Arbitrary Waveform Generators (AWG's) have also been used. AWG's, however, respond slowly to changes in the pulse timing and amplitude required for mimicking the tailpulses produced by radiation detectors. Additionally, efforts to duplicate the pileup effect, i.e. summation of tailpulses, have been largely unsuccessful.
There is therefore a need for tailpulse generators/simulators capable of producing electronic pulses which realistically simulate tailpulse signals produced by radiation detectors by including the effects of pulse pileup and random or near-random pulse timing.